A highly sensitive endotoxin sensor based on redox cycling in a nanocavity

Area of Science:

• Electrochemistry
• Biosensing
• Nanotechnology

Background:

• Endotoxin detection is crucial for preventing bacterial infections.
• Existing methods for endotoxin detection can be time-consuming and lack sensitivity.
• The Limulus amebocyte lysate (LAL) assay is a standard method but requires optimization for speed and sensitivity.

Purpose of the Study:

• To develop a highly sensitive and rapid electrochemical method for endotoxin detection.
• To utilize a nanocavity device with redox cycling for signal amplification in the LAL assay.
• To evaluate novel substrates for enhanced electrochemical detection of endotoxin.

Main Methods:

• Fabrication of a nanocavity device using photolithography.
• Development and testing of LGR-pAP and LGR-AMF as substrates for the LAL assay.
• Electrochemical detection of generated pAP and AMF using redox cycling within the nanocavity.
• Quantification of endotoxin using the developed assay and device.

Main Results:

• The nanocavity device enabled sensitive detection of pAP based on oxidation potential differences.
• Detection of AMF was achieved by exploiting differences in diffusion coefficients, demonstrating high redox-cycling efficiency.
• Endotoxin was detected at concentrations as low as 0.2 EU L⁻¹ with the LGR-pAP substrate after 1 hour.
• The LGR-AMF substrate was not effective due to lack of reaction with the clotting enzyme.

Conclusions:

• A highly sensitive and rapid electrochemical endotoxin detection method was successfully developed using a nanocavity device and LAL assay.
• The LGR-pAP substrate demonstrated effective performance, achieving low detection limits.
• The nanocavity platform shows significant potential for simple, rapid, and sensitive endotoxin detection, although substrate optimization may be needed for alternative substrates.